Transmission power control apparatus

• US 7,062,287 B2
• Filed: 02/08/2002
• Issued: 06/13/2006
• Est. Priority Date: 09/22/1999
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Nakamura, Satoshi, Sawada, Kensuke, Kimura, Dai, Kubo, Tokuro, Kawaguchi, Noriyuki, Minowa, Morihiko
• Primary Examiner(s): Corsaro, Nick
• Assistant Examiner(s): Orgad, Edan
• Application Number:
  US10/072,058
• Publication Number:
  US 20020094836A1
• Time in Patent Office: 1,586 Days
• Field of Search: 455/522, 455/69, 455/132, 455/134, 455/135, 455/68, 455/10, 455/41, 455/67.11, 455/67.13, 455/67.15, 455/67.16, 455/524, 455/60, 455/62, 455/63.1, 455/65, 455/506, 455/143, 370/318, 370/320, 375/140, 375/142, 375/144
• US Class Current: 455/522
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile

Abstract

In a transmission power control apparatus for measuring SIR, which is a ratio of a receive signal to an interference signal, and controlling transmission power of a mobile station in such a manner that the measured SIR will agree with a target SIR, a fading detector detects the rate of change in fading, a correction unit corrects the target SIR based upon the rate of change in fading, and a transmission power control command creation unit creates a command for controlling transmission power of the mobile station in such a manner that the measured SIR will agree with the corrected target SIR, and transmits this command. Further, a searcher detects multipath and the levels of signals that arrive via respective ones of the paths, a level-difference calculation unit calculates level differences between the paths, a correction unit corrects the target SIR based upon the level differences between the paths, and a transmission power control command creation unit creates a command for controlling transmission power of the mobile station in such a manner that the measured SIR will agree with the corrected target SIR, and transmits this command.

Claims

1. A transmission power control apparatus in a base station for measuring SIR, which is a ratio of a received signal to an interference signal, and controlling transmission power of a mobile station in such a manner that said measured SIR agrees with a target SIR, comprising:

a searcher for detecting multipath and levels of signals that arrive via respective ones of the paths;

a level-difference calculation unit for calculating plural level differences between mutually adjacent reception levels using the levels of signals;

a correction unit for correcting the target SIR based upon a combination of said plural level differences between mutually adjacent reception levels; and

means for creating a command, which controls transmission power of the mobile station in such a manner that the measured SIR agrees with said corrected target SIR, and transmitting this command to the mobile station.

2. A transmission power control apparatus according to claim 1, further comprising a memory for rounding, as (Lmax−

Ls), levels for which the level difference from a maximum level Lmax is less than a set value Ls, and storing correction values of target SIR in correspondence with combinations of level differences between mutually adjacent reception levels in the order of the reception levels;

wherein said level-difference calculation unit arranges the reception levels of each of the paths of the multiple paths in order of decreasing or increasing size and calculates level differences between mutually adjacent reception levels; and

said correction unit corrects the target SIR using a correction value corresponding to the combination of level differences read out of the memory.

3. A transmission power control apparatus in a base station for measuring SIR, which is a ratio of a received signal to an interference signal, and controlling transmission power of a mobile station in such a manner that said measured SIR agrees with a target SIR, comprising:

a fading detector for detecting rate of change in fading;

a searcher for detecting multipath and levels of signals that arrive via respective ones of the paths;

a level-difference calculation unit for calculating plural level differences between mutually adjacent reception levels using the levels of signals;

a correction unit for correcting the target SIR based upon a combination of the rate of change in fading and said plural level differences between mutually adjacent reception levels; and

means for creating a command, which controls transmission power of the mobile station in such a manner that the measured SIR agrees with said corrected target SIR, and transmitting this command to the mobile station.

8. A transmission power control apparatus according to claim 3, 4, or 6, wherein said fading detector detects the rate of change in fading from a difference between phase of a pilot signal, which has been received from the mobile station before a prescribed time in the past and phase of the pilot signal at the present time.

9. A transmission power control apparatus according to claim 3, 4, or 6, wherein said fading detector detects the rate of change in fading based upon the measured SIR.

10. A transmission power control apparatus according to claim 3, 4, or 6, wherein said fading detector detects the rate of change in fading based upon direction of transmission power control by TPC bits.

4. A transmission power control apparatus in a base station for measuring SIR, which is a ratio of a received signal to an interference signal, and controlling transmission power of a mobile station in such a manner that said measured SIR agrees with a target SIR, comprising:

a fading detector for detecting rate of change in fading;

a searcher for detecting multipath and levels of signals that arrive via respective ones of the paths;

a level-difference calculation unit for calculating plural level differences between mutually adjacent reception levels using the levels of signals;

a BER measurement unit for measuring bit-error rate BER;

a correction unit for correcting the target SIR based upon a combination of the rate of change in fading, said plural level differences between mutually adjacent reception levels and a difference between measured BER and target BER; and

means for creating a command, which controls transmission power of the mobile station in such a manner that the measured SIR agrees with said corrected target SIR, and transmitting this command to the mobile station.

5. A transmission power control apparatus according to claim 4, further comprising a memory for storing correction values of target SLR in correspondence with combinations of rate change in fading and level differences between paths;

wherein said correction unit corrects a correction value, which corresponds to a combination of the rate of change in fading and the level differences between paths read out of the memory, on the basis of the difference between measured BER and target BER, and corrects the target SIR by said correction value.

6. A transmission power control apparatus in a base station for measuring SIR, which is a ratio of a received signal to an interference signal, and controlling transmission power of a mobile station in such a manner that said measured SIR agrees with a target SIR, comprising:

a fading detector for detecting rate of change in fading;

a searcher for detecting multipath and levels of signals that arrive via respective ones of the paths;

a level-difference calculation unit for calculating plural level differences between mutually adjacent reception levels using the levels of signals;

a FER measurement unit for measuring frame-error rate FER;

a correction unit for correcting the target SIR based upon a combination of the rate of change in fading and said plural level differences between mutually adjacent reception levels and a difference between the measured FER and target FER; and

means for creating a command, which controls transmission power of the mobile station in such a manner that the measured SIR will agree with said corrected target SIR, and transmitting this command to the mobile station.

7. A transmission power control apparatus according to claim 6, further comprising a memory for storing correction values of target SIR in correspondence with combinations of rate change in fading and level differences between paths;

wherein said correction unit corrects a correction value, which corresponds to a combination of the rate of change in fading and the level differences between the paths read out of the memory, on the basis of the difference between the measured FER and the target FER, and corrects target SIR by said correction value.